Because the heart of Roxas’ entire being is the hearts of two Keyblade wielders, Roxas can dual-wield Keyblades, Oathkeeper, and Oblivion, quickly demonstrating outstanding swordsmanship skills.
Roxas can wield two Keyblades because he is Sora’s nobody, possessing his own heart as well as Ventus’s. Due to Xion’s existence, Roxas is initially unable to use his Synch Blade, but destroying it awakens the ability, which he activates when he begins his attack on The World That Never Was.
To put it in perspective, Roxas is basically as powerful as Sora at the end of Kingdom Hearts 2 but with the ability to wield two Keyblades, light and dark magic at any time.
Interviewer: “Why can Roxas wield two weapons?” / Tetsuya Nomura: “Sora can wield two Keyblades at the same time because he has Ventus’s and his own. Since Roxas is part of Sora, he can also use two. In Days, Roxas awakened his ability to wield two Keyblades Battle against Xion. Once Sora absorbs him into KHII, he can dual wield as well.”
Assuming you have all the Keyblades in play, Oathkeeper and Oblivion will share the spot for the third best Keyblade. The Ultima weapon is fully upgraded with 13 Strength and 13 Magic with powerful abilities and shapeshifting, making it the best overall weapon in the game.
Gameplay. Surprisingly, Riku is the only one who can wield the Oblivion Keyblade in Kingdom Hearts 358/2 Days, although Roxas can wield it along with Oathkeeper. Riku can equip Oblivion by equipping Pandora’s Gear.
Kairi’s default. Destiny’s Embrace (Destiny’s Embrace, Desutinī Pureisu?, lit. “Destiny’s Place”) is a Keyblade found in Kingdom Hearts II, Kingdom Hearts II Final Mix , Kingdom Hearts: Birth by Sleep and Kingdom Hearts: Birth by Sleep: Final Mix.
The Oathkeeper is created when Sora uses Kairi’s Wayfinder as a keychain. After rescuing her from Hollow Bastion in Kingdom Hearts, Kairi gives him the lucky charm in the secret waterway in Traverse Town.
Two-Handed Keyblades in Kingdom Hearts 3
Just like Roxas in Kingdom Hearts 358/2, Sora has access to the Two-Handed Form once both Keyblades are acquired. This gives Sora the power to wield both the Oathkeeper and the Oblivion Keyblade at the same time.
Physically, Roxas is the same age as Sora, around 15-16 years old. However, being a nobody and having a very short life, he is actually about one to three years old.
Riku was the true master of the Keyblade but chose darkness over light, so the Keyblade chose Sora instead.
For many people in this community, Roxas is considered a fairly powerful Keyblade Hamlet. Much of this comes from his victory over Riku in battle just prior to the events of KH2, before Riku used the power of Ansem SoD to overpower Roxas.
Sephiroth is an optional boss waiting to be challenged in the dark depths of Radiant Garden. This is expected to be a tough encounter, but defeating Sephiroth will grant Sora the Fenrir (a powerful Keyblade).
In an interview with Tetsuya Nomura, as well as various novelizations of the game, it is revealed that this resemblance is due to Sora’s heart connecting to Ventus at the start of the game and someone else having connected to Ventus’ Heart, would Vanitas look like that person.
However, Sora still gained the ability to wield the Keyblade when he held out his heart to Ventus after feeling Ventus’ shattered heart. By binding his heart to Ventus’s, he gained the ability to wield his own Keyblade as well as Ventus’s.